Surface activator for redox-initiated adhesives

Abstract

Activator compositions for redox-initiated cure of adhesive compositions of ethylenically-unsaturated monomers which comprise the condensation reaction product of an alpha-hydroxy ketone, e.g., benzoin, and a primary amine, and preferably a transition metal salt. Also two-part adhesive compositions comprising such activator compositions and a process for bonding two or more adherends with such activator compositions.

What is claimed is: 
     
       1. A curable two-part adhesive composition comprising: (A) a first part which comprises a solution of at least one ethylenically-unsaturated monomer capable of redox polymerization and a free radical initiator; and   (B) a second part which comprises an activator composition comprising a condensation product of an α-hydroxy ketone and a primary amine.   
     
     
       2. The adhesive composition of claim 1 wherein said α-hydroxy ketone has the formula: ##STR2## wherein R 1  and R 2  are independently selected from phenyls, substituted phenyls, and alkyls. 
     
     
       3. The adhesive composition of claim 1 wherein said α-hydroxy ketone is benzoin. 
     
     
       4. The adhesive composition of claim 1 wherein said primary amine has the formula:   R.sup.3 NH.sub.2     wherein R 3  is an alkyl having from one to 12 carbon atoms.   
     
     
       5. The adhesive composition of claim 1 wherein said primary amine has the formula:   R.sup.3 NH.sub.2     wherein R 3  is an alkyl having from four to six carbon atoms.   
     
     
       6. The adhesive composition of claim 1 wherein said condensation product is the product of between about 1 and about 2.5 equivalents of said amine per equivalent of said α-hydroxy ketone. 
     
     
       7. The adhesive composition of claim 1 wherein said activator composition further comprises a transition metal salt. 
     
     
       8. The adhesive composition of claim 7 wherein said transition metal salt contains at least one of the following metal atoms: vanadium, molybdenum, cobalt, copper, or iron. 
     
     
       9. The adhesive composition of claim 7 wherein said transition metal salt is one of vanadium oxide (acetylacetonate) 2  or vanadium acetylacetonate. 
     
     
       10. The adhesive composition of claim 7 wherein said activator composition comprises up to about 50 parts by weight of said transition metal salt per 100 parts by weight of said primer composition. 
     
     
       11. The adhesive composition of claim 7 wherein said activator composition comprises between about 10 and about 40 parts by weight of said transition metal salt per 100 parts by weight of said primer composition. 
     
     
       12. The adhesive composition of claim 1 wherein said ethylenically-unsaturated monomer is selected from at least one of acrylates, methacrylates, acrylamides, and methacrylamides.